1.Field of the Invention
The present invention relates to a semiconductor device and method for the semiconductor device including a nonvolatile semiconductor memory.
2.Description of the Related Art
A NAND type flash memory is known as one of nonvolatile semiconductor memories (Jpn. Pat. Appln. KOKAI Publication No. 2002-359308). The NAND type flash memory comprises a memory cell region and a peripheral circuit region provided at outer periphery of the memory cell region. Among the highly downsized NAND type flash memories, there is a commercially available NAND type flash memory which includes a dummy cell region provided at the periphery of the memory cell array region.
The dummy cell region is a region which is provided for ensuring required lithography margin. That is, if no dummy cell region exists, an active area at an edge of the memory cell array region can not be formed in the minimum dimension because of lithography margin.
It is in a similar situation even in the NAND type flash memory including a dummy cell region, if downsizing further advances in the future, there is a concern that device characteristic is lowered in the memory cell region too.